One afternoon, when Ross was over at the club-house, where he spent so much of his spare time, Anton pointed out that the conditions were ripe for a killing frost. "The hottest to-day was sixty-two degrees," he said, "and you remember Mr. Levin told us that one wasn't ever safe unless the maximum was sixty-four. There's not a cloud in the sky anywhere and there's practically no wind, and what there is, Tom told me over Bob's wireless, is from the northwest, and that's the worst quarter. I was just going to take the dew-point when you came in." "Let's do it now, Anton," said Ross. "Got the cup?" For answer the crippled lad took down from the shelf a small tin mug. It was already bright and shining, but he polished it until it looked like silver. "I've got the jug of ice-water ready," he said. Pouring some tap water into the cup, and filling it about one third full, he began to stir it round and round with a thermometer. The mercury in the tube quickly dropped, until it read 50 deg., showing the temperature of the water. "Now, Ross," said Anton, "pour in the ice-water slowly." Ross picked up the pitcher and began to let the water trickle in a tiny stream into the bright tin cup. Anton went on stirring. Steadily the mercury descended in the tube as the water in the cup grew colder and colder. Ross poured in more and more slowly. Then suddenly, quite suddenly, while both boys were watching, the brightness of the tin cup clouded over, as though with a sudden fog. Anton drew out the thermometer and looked at it. "The dew-point's only thirty-four," he cried, "and as we've got to figure frost at three or four degrees lower, it'll be so cold that there won't be any fog to stop a freeze. Ross, it's just the night for a killing frost. What do you think we'd better do?" The older lad hesitated. "If you don't mind, Anton," he said, "I'll stay to supper, and we'll see what your night observations say." By evening the threats of a frost were even more definite and the two boys consulted what had best be done. "I can easily get Father to start his fire-pots," said Ross, "we got them all fixed up this winter. Bob's dad has got some fruit, and we can warn him by wireless, and we could get a lot of the fellows together. I don't want to make a mistake, though. If we suggest that the fire-pots ought to be started and then it doesn't freeze, we'll hurt the League a lot more than we'll help it." "I wish we could talk it over with Mr. Levin," said Anton, "but he's down with one of his sick spells and we oughtn't to disturb him. Whatever we do, we've got to do it on our own." "Let's get Bob here," suggested Ross, "he's got a steady head." "And Fred," Anton added, "he's read all the Weather Bureau stuff on Frosts, I know. He's been writing his articles for the _Review_ from them." "All right," said Ross, "I'll slip over and call for Fred and you get Bob on the wireless and ask him to come over here."